About

A free, open-source, ad-free chromatic tuner. Bass and guitar.

Why this exists

Mobile tuner apps are usually freemium — the actually useful features (alternative tunings, adjustable A₄ reference, no ads) sit behind a paywall. This app keeps them free for everyone.

What it does

• Bass — 4 & 5 string. Standard, Drop D, Drop C, ½ step down.
• Guitar — 6 & 7 string. Standard, Drop D, DADGAD, Open G, ½ step down.
• Custom A₄ — slider 415–466 Hz plus 1-tap presets 431 / 432 / 440 / 441 for alternative reference tunings (Radiohead's "No Surprises" is A₄=431, for example).
• Auto-detect — play any string, the tuner finds the closest target.
• Manual lock — tap a string button to pin the tuner to that target.
• Offline — installs as a PWA, works without network after first visit.

How it works

The browser's microphone is captured via Web Audio API. Each frame, a 4096-sample window is analyzed using the YIN algorithm (de Cheveigné & Kawahara, 2002): cumulative mean normalized difference function → absolute threshold → parabolic interpolation. A median-of-6 smoothing filter rejects octave jumps and noise. The needle shows cents off the nearest string in your selected tuning.

All processing is local. Nothing leaves your device.

Open source

Full source at github.com/omrihefez/tuner. MIT license. Read, fork, audit, contribute.

Privacy

Privacy policy — short version: we collect nothing.

Built by

Omri Hefez with Meni.